The present invention relates to a method and apparatus for packaging collations of articles and more particularly, but not exclusively, to a method and apparatus for packaging together collations of articles in a production line environment.
It is known to package articles by wrapping them in flexible sheet material such as, for example, highly stretched synthetic plastics film. An article, or a group of articles, is typically enclosed between two sheets of material or a folded single sheet and the material is heat sealed at overlapping edges.
A continuous process for wrapping articles in material of this kind is described in international patent application WO 90/09316 which discloses a longitudinal wrapping machine whereby articles are wrapped by winding a continuous web of wrapping material around the articles in a direction generally transverse to their direction of movement along the machine. This results in the articles being wrapped by a helical continuous web of material. The machine has an upstream conveyor that is separated from a downstream conveyor by a rotary ring-type web applicator whose rotary axis is generally parallel to the longitudinal axis of the conveyors. The articles are fed to the applicator by the upstream conveyor and as they pass through the ring of the applicator at a predetermined speed it rotates and dispenses the wrapping material. As a result, the articles are wrapped by a continuous helical band of material. The wrapped articles pass to the downstream conveyor which carries them to a cutting station, which separates the wrapped articles into individually wrapped articles by cutting through the adjoining wrapping between each article. A longitudinal web of material disposed on the conveyors passes through the applicator and is transported under the articles at the same rate. This web serves to bridge the gap between the upstream and downstream conveyors and the applicator and thus supports the articles as they pass continuously between them.
In some instances, a fixed bracket is provided which extends through the applicator ring substantially from the end of the upstream conveyor to the beginning of the downstream conveyor. The bracket serves to support the material bearing the articles as they are wrapped by the applicator ring. However, where articles are smaller than the distance between the upstream and downstream conveyor, the packs of articles tend to sit on the dead plate until they are pushed onto the downstream conveyor by following articles. This is problematic at the cutting stage because the articles are too close together on the downstream conveyor for the cutting station to be able to operate effectively.
Collations of articles are usually secured together (for example on cardboard pallets and/or wrapped together by packaging tape) before wrapping. However, it may be desirable to wrap collations of articles together which are not secured together before they are wrapped, i.e. “unsecured collations”. The wrapping material therefore serves both to protect the articles for shipping and to hold the articles together in collations. Wrapping collations of articles in this way means that no extra material is required to secure the articles together, which provides significant advantages in cost and efficiency during packaging and shipping. However, the lack of any securement allows the articles to move relative to one another during the wrapping process with the result that the wrapped articles may not be wrapped tightly together. In some cases, such as when the articles have a high centre of gravity, unsecured articles may even fall over before wrapping has occurred, causing costly stoppages in a production line environment.